Hold-over refrigerator unit



Jan, 31, 1939.

Filed March 2l, 1956 all l" 1 ATTO NEYS Patented jan. 3l, i939 UNITED. STATES HOLD- OVER REFRIGERATOR UNIT Wayne D. Jordan, New Rochelle, and Pani D. Van Vliet, Utica, N. Y., asslgnors tol Savage Arms Corporation, Utica, N. Y., a. corporation of Delaware Application March 21,

5 Claims.

The invention relates to intermittently operated refrigerating systems of the kind in winch the refrigerated space is maintained at the required low temperature during stand-by periods of the refrigerant circulating means, by thecooling elect of a so-called hold-over medium, usually a mixture having a relatively low eutectic freeze point and itself cooled by the refrigerant during the periods of circulation of the latter.

Such systems are serviceable in various relations and particularly in the refrigeration of mobile storage compartments, such as automotive trucks, it being customary in such cases to equip the same only with so much of the refrigerant circulating system as comprises the evaporator, and, associated with it, the hold-over medium, the truck being returned periodically to some central station where its evaporator is coupled into a stationary refrigerating system and the latter operated to cool the hold-over medium, preliminary to its'next departure. As Will be understood, the cooling of the storage space while the truck is making'its deliveries is dependent upon the eicacy of the hold-over. l

The object of the invention is an evaporator and hold-over means organized in a single, highefficiency cooling u nit especially suitedto the requirements of mobile installations and, to that end, utilizing a medium adapted to be frozen, rather than merely chilled by the refrigerant, and by reason of its special provisions against rupture by freezing, adapted to hold a larger quantity of such medium and thereby prolong the hold-over period, all as moreparticularly described below.

In the accompanying drawing Fig. 1 is a perspective lView of a preferred form of the new unit partly in section, and Figs. 2 and 3 are sectional part views, on the lines II-II and III-III respectively of Fig. 1 and on a larger scale.

While capable of application to the cooling of a variety of types of storage space and, in consequence, subject to installation in numerous ways, the unit may be assumed to be suspended from the roof of the storage space, a truck-body for example, by means of appropriate hangers, not shown. It comprises upper and lower plate sections I and 2, of sheet metal, having their flat, marginal portions shaped for Welded or sealed attachment each to the other and, within such margins, having one or more indentations or channelspressed or otherwise formed therein to provide interconnected spaces or passages between the plates. -These passages 'are for the refrigerant. The construction of the two plates 1936, serial No. '10,078

( Cl. sz-95) and the passages formed by them is subject to any modification as thought best suited to the nature of the refrigerant employed or the conditions of use. As shown, the complementary channels 3 and 4 provide a continuous zigzag or tortuous duct (indicated by the dotted line in Fig; 1) for thepassage of the refrigerant. The adjacent sections of the duct are separated by the flat' surfaces 'l and which may be welded together, and appropriate inlet and outlet fittings 9 and l0 of cast metal are provided at the ends of the duct by means of which the units is coupled into the refrigerant circuit. These are conveniently attached by welding them into notchesl cut into the plates as will be clear in the drawing.

superimposed on the evaporator asthus constructed, and adapted to form therewith a closed compartment for the hold-over medium, is a relatively shallow, inverted shell or tank Il, the yvalls of which are anged and welded or otherwise permanently sealed to the evaporator flange. The hold-over medium is introduced into this compartment through an opening made for the purpose and subsequently closed, but not appearing in the drawing.

It will be apparent that with a unit thus or.- ganized, the cooling effect of refrigerant in the evaporator is applied coincidently to the cooling of the storage space, by reason of the exposure thereto of the surface of the lower plate 2 and to the cooling of the hold-over medium in' tank ll, by reason of the exposure thereto of the upper surface of the upper plate l In consequence, the cooling of the storage space begins immediately upon the passage of refrigerant through the unit,v without Waiting for the hold-over medium to become frozen and continues while the freezing of the latter is going on. This instant chilling is important in the refrigeration of truck bodies because, since long intervals are liable to occur between active periods of refrigeration, a relatively large body of hold-over medium is required to be used, which large body requires considerable time to be cooled or frozen during which ice-cream or other perishable material remaining in the truck might spoil were it not promptly cooled by the evaporator.

Such long intervals as are apt to occur also make desirable the utilization of a hold-over medium which is adapted to be frozen rathero be held within closer Such a. medium is u proposed to be used in the unit illustrated, the dotted line I3 (Figs. 2 and 3) indicating the level to which the tank is filled and the space left for expansion of the medium upon freezing.

Freezing mixtures appropriate for the purpose are relatively poor conductors of heat and accordingly finning is provided for insuring effective heat transfer to the upper plate from the more remote parts of the hold-over tank, such finning being applied over the whole top surface of the upper plate and projecting upwardly from it into close proximity to the top wall of the tank. It is preferable in the form of ribs or fins which, as shown, are the upstand-ing flanges I4 of sheet metal channel members which extend substantially the full length of the upper plate. The flat webs I5 of these members are seated fiat on the fiat tops of the refrigerant channels and in good metal to metal contact therewith, produced by welding or the like, so as to provide effective heat transfer paths between the evaporator and all parts of the freezing-solution. It is noted that the fin members or channels Ill- I5 are welded to the plate member at points, I 5, occurring at intervals along their length, this separation of the points of attachment being desirable in order that the effect of temperature differences may be to some extent `taken up by the unattached portions between welds and thus avoid an objectionable tendency to warp the whole structure of the unit.

The freezing of the mixture begins at the surface of plate I and on the surfaces of the ns, progressing generally upward and to some extent laterally from the surfaces of the ns. The upper part of the mixture is the last to freeze, and, With the unit horizontal, the expansion can occur into the space left for that purpose, resulting in no undue strain on the structure. But if the unit is not in a horizontalposition during freezing (and it is not always convenient to maintain it so in truck installations) the mixture level may assume some such position as is indicated by the dotted line I6 in Fig. 2, in which case it might happen that as the freezing progresses toward and aproaches the top of the tank where the mixture is in contact therewith, pools of unfrozen mixture would be formed, separated from one another or at least from the expansion space by portions of the mixture already frozen, and that upon the freezing of these pools the unit would be subjected to serious stresses liable to rupture it and certainly to weaken it. In order to avoid any such condition and still retain the advantage of large area heat transfer members, provision is made to prevent the formation of isolated pools of unfrozen mixture by so locating or forming such members as to retard the freezing of the mixture along predetermined paths communicating with the expansion space even when, due to a non-horizontal position of the unit, the surface of the mixture is as indicated by dotted line I6.

In the preferred form illustrated, a series of notches or scallops I'I is formed in each of the fins I4 so that only at intervals, and as projections I8, do the fins extend into close proximity to the top wall of the tank. The notches in the respective fins are in substantial alignment. The freezing of the mixture is thus retarded in the vicinity of each notch and, provided the notches are of adequate size, connected zones of delayed freezing will occur, extending fromone side of the unit to the other and, as thefireezing of the mixture progresses, these zones will constitute channels or paths of expansion permitting free movement of the lastto-freeze portion of the mixture toward the expansion space, at whichever side of the unit it may happen to be. 'I'hus under no condition is the light weight tank ever subject to an excessive stress, while a large quantity of hold-over medium can be quickly frozen by virtue of the extended surface and good heat paths provided by the sheet metal fins.

Except as specified in the narrower claims there is no intendedlimitation of this patent to fin structure of the particular design taken for illustration nor to the particular arrangement of the heat paths by which the space above the mixture is kept available to accommodate the expansion, although the channel form of fln structure has special advantages in respect to economy of manufacture and general durability as will now be apparent.

We claim:

1. A cooling unit of the character described comprising in combination upper and lower plate sections having their marginal portions sealed to each other and forming a refrigerant space between them, a third plate section superimposed on said upper plate with its edges sealed to the marginal portion of such plate thereby forming with it a closed compartment for a freezing mixture, a plurality of sheet metal fin members upstanding from the top surface of saidupper plate and extending substantially to the top of said compartment, said fin members having notches formed in the upper edges thereof.

2. A unit of the character described comprising in combination a bottom plate having a continuous, tortuous channel formed therein, with flat plate surfaces surrounding the channel and spacing the adjacent portions thereof, a top plate overlying the bottom plate and having a channel therein complementary to that in the said bottom plate, with flat surfaces sealed to said surrounding andspacing surfaces of the bottom plate, an inlet to and an outlet from the respective end portions of the channel space to permit the circulation of a refrigerant therethrough, a relatively shallow, inverted tank superimposed on said top plate and adapted to form therewith a closed compartment for a freezing mixture, and a plurality of sheet metal channels secured by their webs to the upper side of said top plate and with their flanges extending substantially to the top of said compartment, said flanges having notches formed in the upper edges thereof.

3. A hollow, plate-like, cooling unit, having an intermediate wall dividing the interior into an upper compartment for freezing mixture and a lower compartment for refrigerant, said upper compartment being partially filled with freezing mixture with an expansion space above, and a plurality of heat transfer members extending from the upper surface of said wall toward the surface and last-to-freeze part of the mixture in the-upper compartment and into close proximity to the top of such compartment at points spaced apart both longitudinally and transversely thereof.

4. A hollow, plate-like, cooling unit, having an intermediate wall dividing the interior into an upper compartment for freezing mixture and a lower compartment for refrigerant, said upper compartment being partially filled with freezing mixture with an expansionspace above, and a and last-to-treeze part of the mixture in the upper compartment.

5. A combined evaporator and hold-over device comprising two sheet metal sections united to deine a refrigerant space between them, a third section mounted above and united to the others to form' an adjacent hold-over tank. and

sheet metal iins in said hold-over tank welded to the top wall of the refrigerant space at points spaced apart along the lengths of said tins and extending upwardly in the tank toward the surface of a medium therein.

WAYNE D. JORDAN. PAUL D. VAN VLIET. 

